It's been quite a journey for Andrew McMahon, a fact reflected in the soul-searching lyrics of his first two Jack's Mannequin albums. Their punchy, richly arranged pop-rock purveys a sunny demeanor and big hooks, counterbalancing the earnest introspection of his confessional lyrics and giving them an anthemic, everyman quality.

It's not that McMahon's a drama queen, it's just that songs have been his diary since childhood.

"The first song I wrote when I was 9 years old was about my uncle who had just passed away. It's like the entire mechanism for me to cope and catalog," says the California musician, who's now 28. "There's obviously nothing rare about that, if you look at my albums over the years and how I've chosen to express myself."

During his late teens and early 20s, McMahon was the piano-playing lead singer of catchy alt-rockers Something Corporate. As the band moved toward its eventual implosion, McMahon started working on songs that would become Jack's Mannequin's first album, 2005's Everything in Transit.

"The edges were fraying around Something Corporate," he recalls. "We weren't getting along as well anymore, and I started to feel like, 'Wow, if I'm really going to continue to do this thing that is the source of so much happiness for me, I might have to do it a different way.'"

Written when he was 22, Everything in Transit documents a search for identity that took a turn on the last day of recording, when he was diagnosed with leukemia. He documents the subsequent struggle on 2008's follow-up, The Glass Passenger. Though his cancer's now in remission, he still feels its impact.

"It definitely takes a lot from you. It robs you of a lot of confidence, especially encountering it in my 20s," McMahon says. "I've harbored, at different times in my recovery, a sense of resentment for the fact that I lost what I consider such a critical period of time, or at least it was corrupted by these thoughts of mortality and the fear for your own survival.

"It cuts deep, and I would be lying to say it's not a part of my daily life, still reconciling that it really happened and everything that's followed."

Jack's Mannequin's forthcoming third album, People and Things, finds him continuing to wrestle with his sickness and its imprint on his life, only from a different perspective.

"I had a marriage that was struggling along while I tried to sort out all these things," he says, noting that this next album was written with "more perspective and less of an open wound."

"I think People and Things ends up sort of more honestly telling the story of what it actually looked like."

These days, McMahon's still basking in the afterglow of last year's Something Corporate reunion tour, which practically sold out before it started. It was a gratifying experience, and everyone got along.

"It was just very natural, us getting out there, because there really was no pretense," says McMahon from his now-broadened perspective. "We didn't have anything to prove."